The thrust of this proposal is the development of small, economical, "table-top" accelerators for the production of the short-lived radioisotopes for the powerful medical diagnostic techniques, based on positron emission tomography (PET), which have proven effective in monitoring physiological processes in the body, including brain imaging and visual processing. It draws upon recent advances in linear accelerator technology, a new rf-focused drift tube linac structure (to be developed under this effort), and some rf power source innovations. The principal technical innovations are the higher frequency (800-MHz), which reduces the size of the device and its rf power dissipation, the stronger rf focusing throughout, which reduces the proton beam diameter and improves the energy transfer process, and the single-tank, single- frequency configuration, which allows consideration of a very economical rf power system. A significant part of the effort will directed to the development of a new rf-focused drift-tube (RFD) linac structure. First- order analyses of the performance of each individual component and their performance in combination, will be accomplished. A tentative design for a compact, economical 12-MeV accelerator system for the production of short-lived radioisotopes for the medical community will be produced. Performance and cost estimated for the system will be prepared. Successful completion of this project offers a dramatic reduction in the size, cost and complexity of small proton linacs for isotope production and other medical applications. PROPOSED COMMERCIAL APPLICATION: The potential commercial applications of the research will be the development of a family of small, commercially viable, proton linacs for medical and industrial applications. The principal medical application is the production of short-lived radioisotopes for positron emission tomography (PET). Another significant medical application for these devices would be as an injectors for proton synchrotrons to produce the higher energy protons required for proton therapy.